Is there a book about the Imperial family's jewelry?
Also, can someone explain about Japanese personal decoration and ornamentation (lack of wearing lots of jewelry)? I know very little about it.
And, is there a list of contemporary Japanese jewelers-- other than Mikimoto?

Jewels aren't worn with kimono, except possibly for an obidome, which is a sort of brooch worn on the obi (the sash round the waist). Necklaces and brooches aren't worn with kimono, and hair ornaments tend to be traditional. The outfit itself was considered decorative enough. Since there wasn't a long history of being able to wear jewels with traditional Japanese clothes and since there wasn't much contact with the western world until the mid-19th century or thereabouts, I suppose it isn't surprising that the Japanese royal family doesn't have much in the way of heirloom jewels.

I wonder if the word obidome is originated from the Latin abdomen and appeared in Japanese vocabulary via Portuguese Jesuits in the middle of the 1500's. And if so, this kind of brooch could either started to be used by foreign influence or just named by it.

The Magatama, or Comma-shaped jewels, has been very important to the Imperial Family of Japan. Magatama are ancient Jewels that has been worn by the Japanese since the prehistoric Jomon Period (14,000 BC - 300 BC). A Magatama called Yasakani no Magatama, is part of the Imperial Regalia of Japan, added some time around the Heian period (794 - 1185 AD). The Yasakani no Magatama stands for benevolence, and is one of the three items used in the ceremony of imperial ascension. In Japanese mythology, the jewels, along with the mirror, were hung on the tree outside of Amaterasu's cave (where she had hidden) to lure her out. It is believed to be a necklace composed of jade magatama stones instead of a solitary gem as depicted in popular culture. It is believed to be enshrined in Tokyo, in the Japanese Imperial Palace.

Here is a picture of various Magatama. Some of them are made of jade (hisui in Japanese):

A sun-shaped golden tiara, called a Hirabitai, is usually worn by Crown Princesses of Japan upon their marriage to Crown Princes. They wear Hirabitai together with their Junihitoe, or the Japanese Ceremonial Kimono.

All the pieces for wear with obi are named as such: obi-age, obi-jime, obi-dome, obi-makura, and so on...

I also wanted to point out something I noticed in kathia_sophia's collage of Empress Michiko's tiaras, the center one has a very predominant theme of "Kiku", or Chrysanthemum, which is generally a flower used in fall, or more specifically, October.

All the pieces for wear with obi are named as such: obi-age, obi-jime, obi-dome, obi-makura, and so on...

Thank you for your answer. I am absolutely fascinated with etymology. We have a lot of Japanese immigrants here in Brazil and I have learned that their usage of "Nè" at the end of a sentence when in conversation means "não é?" (something like isn't it? in Portuguese that they have adapted from the Portugues jesuits in the Middle Age.